Self-contained fluid evacuator

ABSTRACT

A self-contained wound evacuator is disclosed which provides a substantially constant negative gauge pressure and which includes a substantially rigid container and an air inflatable member within the container, the container and inflatable member having a combined configuration which avoids deformation of the inflatable member by the container in at least one direction of expansion of the inflatable member. Means are provided for inflating the inflatable member and controlling the deflation thereof.

United States Patent Nehring June 17, 1975 l l SELF-CONTAINED FLUID EVACUATOR 75 Inventor: John R. Nehring, Woodcliff Lake, P "7 '7 Gaude NJ. Assistant ExammerHenry S. Layton Attorney. Agent, or FirmFinnegan, Henderson, [73] Assignee: international Paper Company, New Fa b & G tt York, NY.

[22] Filed: Nov. 19, 1973 [57] ABSTRACT [21] Appl. No.: 417,124 A Selficontained wound evacuator is disclosed which provides a substantially constant negative gauge pressure and which includes a substantially rigid container U-Sn i u I I e l i n ll'll. container and inflatable member having a combined [58] F'eld Search 7' configuration which avoids deformation of the inflat- 128/302 417/394 222/3865 able member by the container in at least one direction of expansion of the inflatable member. Means are pro- [56] References cued vided for inflating the inflatable member and control- UNITED TATE PATENTS ling the deflation thereof.

2,074,223 3/1937 Horiuchi H 417/394 3,032,037 5/1962 Huber l2S/276 22 9 Dmwmg FIG. 6

SELF-CONTAINED FLUID EVACUATOR BACKGROUND This invention relates to fluid evacuators and, more particularly, to such evacuators which are disposable, portable and self-contained.

The evacuation of fluids from the body of a patient is a common medical practice. For example, the removal of fluids from the vicinity of a wound has been found to aid faster and firmer healing and reduce the likelihood of infection, fever and patient discomfort. Fluid evacuation usually is accomplished through gravity drainage, pressure dressings, compression bandages or by negative pressure, the latter being preferred. Conventional continuous closed wound suction devices include power driven vacuum pumps, central suction systems or evacuated bottles. With the exception of the evacuated bottle, each of these systems has many disadvantages because of their cost, noise and restriction of patient mobility resulting in the retardation of post operative exercises, ambulation and rehabilitation.

Other suction wound drainage systems were developed to overcome these disadvantages. Examples of more recent commonly used wound evacuators are shown in US. Pat. Nos. 3,l15,l38 and 3,376,868. In both of these devices the evacuator comprises an evacuation chamber formed with resilient side walls which, after manual compression and release, tend to return to their original extended position. In so returning they provide a reduced pressure on the interior of the container which, when attached to the patient by means of a tube, effects evacuation of the wound. A potential hazard with such a device is the possibility of accidental compression of the container at a time when compression is undesirable. Accidental compression when the device is attached to the patient could result in the injection of air or previously removed fluids into the patient. Another disadvantage with devices of this type is their wide variation of negative pressure over the specified filling range of the devices. When empty and fully compressed these devices often provide a vacuum higher than necessary which might cause lesions if tissue is sucked into or against the drainage tube. On the other hand, as the container becomes filled with fluid the vacuum is reduced often to a level where the vacuum is relatively ineffective and clots or other debris may clog the drainage tube. Wound evacuators presently commercially available have total pressure variations of about l30% or more.

Accordingly, it is an objective of this invention to provide an inexpensive, reliable, disposable, portable, self-contained vacuum drainage device which evacuates fluids from wounds at relatively constant pressure throughout the entire operating range of the device.

It is another objective of this invention to provide an improved self-contained wound evacuator which cannot be easily accidentally pressurized thereby avoiding accidental injection of air or fluids into a patient.

Additional objectives and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and advantages of the invention may be real ized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE INVENTION To achieve the foregoing objectives and in accordance with the purpose of the invention, as embodied and broadly described herein, the self-contained fluid evacuator of this invention comprises a substantially rigid, closed container having first and second openings therethrough, the first opening being adapted to receive a conduit, an inflatable member within the container, means for inflating the inflatable member mounted on the container and being in flow communication with the interior of the inflatable member through the second opening. Valve means are provided which are responsive to the difference in pressure between the pressure in the inflation means and in the inflatable member such that the valve means enable fluid to enter the inflatable member from the inflating means at a higher rate than the fluid can leave the inflatable member.

Preferably, the valve means is a check valve having a bleed passageway therethrough which permits restricted fluid-flow through the valve when the valve is closed. It is also preferred that the inflating means is a manually operable pump having an outlet and that the inflatable member is a resilient bladder attached to the outlet of the pump with the check valve being mounted across the pump outlet.

In accordance with the other embodiments of this invention, a fluid evacuator comprises a substantially rigid, closed container including a bottom wall, first and second spaced apart opposed side walls, third and fourth side walls joined to the opposite ends of the first and second side walls, the third and fourth side walls being spaced apart a distance greater than the spacing between the first and second sidewalls. The evacuator further includes a port communicating with the interior of the container, an inflatable member within the container, means for inflating the inflatable member, means for deflating the inflatable member and wherein the third and fourth side walls have a configuration which substantially conforms to the shape of the natural unimpeded shape of the adjacent portion of the inflatable member during inflation of the inflatable member effecting substantially constant negative pressure at the port during inflation of the inflatable member.

Preferably the configuration of the third and fourth side walls either actually conform to the shape of the adjacent portion of the inflatable member or effectively conform to that shape through control of the pressure within the container.

The invention consists in the novel parts, constructions, arrangements, combinations and improvements shown and described. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate several embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS Of the drawings:

FIG. 1 is a perspective view of a wound evacuator formed in accordance with this invention;

FIG. 2 is a sectional view taken along line 22 of FIG. 1;

FIG. 2A is a sectional view taken along line 2A2A of FIG. 2;

FIG. 3 is a sectional view taken along line 3-3 of FIG. 1;

FIG. 4 is an enlarged, partially cutaway. perspective view of the throat portion of a pressurized air source formed in accordance with one form of this invention;

FIG. 5 is an empirical pressure vs. volume curve of cylindrical latex bladder within a rigid container formed in accordance with this invention;

FIG. 6 is an enlarged sectional view of a portion of the wall of the wound evacuator container having a roughened interior surface;

FIG. 7 is an enlarged sectional view of a portion of the wall of the wound evacuator container having a coating on the interior surface thereof; and

FIG. 8 is an enlarged, partially cutaway. perspective view of a pressurized air source formed in accordance with a second form of this invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Throughout the specification and claims, terms of orientation, such as front, back, up and down are employed with respect to the orientation shown in the drawings in order to simplify description of the invention and are not intended to limit the location or direction of the elements with respect to which these terms are used.

In accordance with the invention, the wound evacuator includes a housing and a first port serving as a fluid inlet port communicating with the interior of the hous ing. The first port is adapted to receive a tube designed to be placed internally within a patient adjacent to a wound in order to remove fluids from the vicinity of the wound. As here embodied, a self-contained wound evacuator 10 is formed with a container 12 having opposed first and second side walls l6, l8 (hereinafter called front and back walls), opposed third and fourth side walls 20, 22 adjacent to the front and back walls l6, l8 and a bottom wall 24. The container 12 is relatively rigid, which means that it will not deform substantially when it is subjected to the normal forces to which devices of this sort are expected to be exposed. The container 12 is provided with at least one opening, such as port 26, extending through and communicating with the interior of the container 12. The port 26 is adapted to receive flexible tubing 28 which is to be inserted into a patient adjacent to the wound being treated. The tubing 28 is conventional wound tubing which is non-toxic, non-pyrogenic. inert, non-porous and non-degradable when used in its intended environ ment and which has a plurality of openings 29 at its dis tal end.

While a single port 26 is sufficient for operation of the selfcontained wound evacuator 10 as described below, it is preferred that a second opening or port 30 be provided to serve as an outlet port to permit expulsion of air contained within the container 12 and to permit removal of fluid which is received within the container 12 during utilization of the wound evacuator 10. A suitable closure or cap 32 is provided to permit selective opening and closing of the second port 30.

In accordance with the invention an air inflatable member is mounted within the container 12 and means for inflating and deflating the inflatable member are provided. As here embodied, the inflatable member is a resilient bladder having an opening at one end 42 thereof. The means for inflating the bladder 40 preferably is a manually operated pump, such as a handoperated bulbous resilient member having a resiliency at least only slightly greater than the resiliency of the bladder 40. Such a resiiient member is a rubber bulb 44 having an air inlet 46 and an open neck 48. The open end 42 of the bladder 40 is mounted in the neck 48 of the bulb 44 so that air expelled through the bulb neck 48 is forced to enter the bladder 40. While the bladder can be mounted directly on the walls of the bulb neck 48, the embodiment illustrated in FIG. 2 4 employs a plug 50 which is force-fitted within the neck 48, the plug 50 having an air passageway 52 axially therethrough. The plug 50 is provided with an annular recess 54 to receive the open end 42 of the bladder, the open end of the bladder being trapped between the exterior of the plug 50 and the interior of the bulb neck 48 to fixedly hold the bladder in place. The bulb 44 serves as the means to inflate the bladder 40 while the resiliency of the bladder serves as the means for deflating the bladder.

While the bulb air inlet 46 is shown at the top of the bulb 44, it could be located at any other position. For example, with a container 12 as shown, locating the air inlet on the side has been found particularly convenient because it is easier to block the air inlet 46 with a finger or the heel of a hand. Furthermore, in order to ensure quick opening of the inlet 46 on release of the bulb so that the bulb quickly refills with air entering through the inlet 46 rather than being withdrawn from the bladder 40, an irregular surface. such as a bead 51 is pro vided through which the inlet is formed. The bead SI prevents the finger or hand from sealing the inlet during return of bulb to normal unsqueesed condition.

Further in accordance with the invention, valve means are provided which are responsive to the difference in pressure between the bulb 44 and the bladder 40 so that when the pressure in the bulb exceeds the pressure in the bladder. the valve means permit free flow of air from the bulb to the bladder. However, when the pressure in the bladder 40 exceeds the pressure in the bulb 44. the valve means restrict the flow from the bladder to a predetermined minimal flow rate.

In order to control the rate of deflation of the bladder 40, a slow leak check valve, such as a flapper valve 56 having a small diameter bieed vent 58 therethrough, is mounted on the bladder side of plug 50. When the bulb 44 is squeezed. the flapper valve 56 permits air to be expelled freely from the bulb into the bladder 40 since the pressure differential across the flapper valve 56 during such an operation forces the flapper valve away from the plug 50 thereby permitting air to flow easily into the bladder 40. However, when the bladder is partially or totally inflated and the bulb 44 is returning from its squeezed or collapsed position to its normal or expanded position, the pressure within the bladder is higher than the pressure within the bulb and the flapper valve is forced against the plug 50 thereby obturating the air passageway 52 except for the vent S8 and preventing most of the air from leaving the bladder 40. After the bladder is fully inflated and the wound tubing 23 is inserted in a patient for evacuation, the small bleed vent 58 permits air to be expelled from the bladder 40 through the passageway 52.

To utilize the self-contained wound evacuator 10 of this invention the distal end of the wound tubing 28 is inserted in the patient before the proximal end is con' nected to the inlet port 26. Alternatively, the wound tubing can be connected to the container 12 and closed by a conventional pinch clamp (not shown). The closure 32 is removed from the outlet port 30 and the bladder 40 is inflated by alternately squeezing and releasing the bulb 44. When squeezing the bulb 44 the user covers the air inlet 46 to prevent air from being expelled through the inlet, thereby requiring that all air expelled from the bulb 44 passes through the air passageway 52 into the bladder 40. When the bulb is released air enters the bulb through the inlet 46. The flapper valve 56 prevents a substantial amount of air from flowing from the bladder 40 back into the bulb 44. Continued pumping of the bulb inflates the bladder 40 which forces the air within the container 12 out through the outlet port 30 until such time as the inflated bladder substantially fills the container 22. At that time, the proximal end of the wound tubing 28 is connected to the inlet port 26 (or the pinch clamp is opened) and the closure 32 is placed in the outlet port 30 thereby closing the port. As the bladder deflates, the air in the bladder passes outwardly through the bleed vent 58, the air passageway 52 and the bulb air inlet 46. Deflation of the bladder 40 produces a negative pressure at the port 26 which causes fluids in the vicinity of the openings 29 at the distal end of the wound tubing 28 to pass through the tubing into the container 12.

After the container 12 is filled with body fluid, the closure 32 is removed from the port 30 and the container is emptied, either by gravity feed (pouring the fluid out through the port) or by attaching the port 30 to the low pressure side of a pump and pumping the fluid out. The body fluid can also be expressed from the container 12 by closing the pinch clamp and pumping the bulb 44. As the bladder inflates, it forces the body fluid out of the container and, when empty the bladder is fully inflated and the wound evacuator is ready for reuse. If only a single port 26 is used, the container is drained through the port 26.

In order to provide substantially constant negative pressure at the inlet port 26 throughout the entire operating range of the wound evacuator 10, and to utilize substantially the entire volume of the container, the container 12 and the bladder 40 should have a combined actual or effective configuration so that the container does not physically interfere with or distort the inflation of the bladder 40 in at least one direction of inflation. The terms constant pressure and substantially constant pressure as used throughout this specification and in the claims are intended for use in a relative sense and do not imply absolute constant or unchanging pressure. For example a total pressure variation of up to about 30% throughout about 90% of the deflation range is acceptable.

A low profile container 12 (relatively narrow from front 16 to back 18) is preferred because it can be more comfortably and conveniently worn by a patient or attached to a support, such as a bed or chair. These advantages can be obtained if the front and back walls l6, 18 are substantially flat and relatively closely spaced apart. Substantially flat front and back walls are walls which either are truly flat or which have a radius of curvature much greater than the radius of the bladder 40 when the bladder contacts the front and back walls 16, 18. Where a substantial vacuum is to be induced in the container 12, it may be preferred to form the front and back walls l6, 18 with a shallow outward curvature (large radius of curvature) to provide structural strength without adversely affecting the low profile of the container.

It also is desirable to be able to stand the container 12 vertically on a flat surface and, therefore, the bottom wall 24 of the container preferably should be flat.

It has been found that satisfactorily constant pressure can be obtained with a cylindrical bladder when the bladder is inflated in a low profile container (flat" front and back walls) if the side walls 20, 22 adjacent to the flat" front and back walls 16, 18 actually or effectively conform to the shape of the inflated bladder 40.

In order to actually conform the side walls 20, 22 to the bladder shape, the side walls 20, 22, are formed with a transverse outward curvature (from front wall to back wall) as can be seen in FIG. 2A. Preferably, the radius of transverse curvature is W /Z where W, is the distance between the front and back walls 16, 18. It also is desirable to avoid corners at the top and bottom of the side walls and, therefore, rounded upper and lower ends are formed or, alternatively, the side walls 20, 22 can be formed with a longitudinal curvature from top to bottom as can be seen in FIGS. 1 and 2.

While satisfactory results can be obatined over a relatively wide range of front-to-back wall spacing, more consistently reliable results and more useful filling volume for a given container size while maintaining rela tively constant pressure can be obtained if the front and back walls l6, 18 are spaced apart a distance greater than twice the diameter of the uninflated bladder (W 2D,).

In accordance with this invention, instead of actually conforming the sidewalls 20, 22 to the inflated bladder shape, the side walls 20, 22 can be made to effectively conform to the bladder shape by controlling the pressure within the container. More specifically, as the bladder 40 is inflated, the air inside the container 12 is expelled through the outlet port 30 until, after the bladder contacts the side walls 20, 22 and continues to inflate, it reaches a position within the container wherein the bladder is about to be forced into a shape which is different from what it would be if the side walls 20, 22 were nonexistent. At that time, the outlet port is occluded to prevent further expulsion of air from the container 12. Any further pressurization of the bladder 40 by pumping the bulb 44 results in a concommitant increase in pressure inside the container since the air cannot escape. Upon release of the bulb 40 the pres sure in the bladder and container rapidly drops to atmospheric pressure by virtue of the air in the bladder 40 escaping through the check valve bleed port 58 and bulb air inlet 46 to the atmosphere. This concept of pressure equalization in the container and bladder when the bladder is about to be deformed into a shape which adversely affects a constant pressure curve is referred to throughout the specification and claims as effective conformation of the container shape with the bladder shape.

As here embodied, the outlet port 30 is occluded by the bladder 40 when it reaches its predetermined shape. This is effected by forming the outlet port 30 with an inwardly extending protuberance 31 which projects inwardly an amount calculated to bring it in contact with the bladder at the appropriate bladder inflation level. The outlet port 30 and protuberance 31 can be formed as an integral part of the container 12 or it can be formed by a separate member mounted in an opening formed in the container 12. When this outlet port occluding concept is employed the shape of the container 12 is not critical.

With respect to a container which actually conforms to the bladder shape and which has a satisfactory low profile, substantially constant negative pressure during deflation of a bladder has been obtained with a container and latex cylindrical bladder having the shapes generally shown in FIGS. 2, 2A and 3 and having the following dimension ratios.

D diameter of bladder;

L;= length of bladder 3.0 4.0 D;

W width of container 2.5 D,

R radius of transverse curvature of side walls D length of container l.8L

P container interior perimeter 220,

The bladder thickness (F together with the characteristics of the bladder material (actually, the modulus of elasticity) determines the vacuum level produced within the container. For a latex bladder, a bladder thickness of 0.0lD; has been found to produce a constant negative pressure in the above described container of approximately 30 inches of water (see FIG. 5). The container perimeter/bladder diameter ratio is calculated to provide not greater than a seven fold increase in bladder diameter which has been found to be within a safe stress range for a latex bladder. For a convenient and comfortable evacuator profile, the bulb diameter (D should be approximately equal to the width of the container (D, W,).

These ratios provide a self-contained wound evacuator having satisfactory performance by providing relatively constant pressure in a desired pressure range (-29 to 35 inches of water) and a safe stress for a bladder made of natural latex. The bladder can also be formed from any synthetic elastomer, such as polyurethane. FIG. 5 is a pressure vs. volume curve of a latex bladder having a three-fourth inch uninflated diameter, a 2 /2 inches free length and a 0.012 inch wall thickness which was inflated in a rigid container having dimensions substantially in accordance with the above dimension ratios. As can be seen, the vacuum within the container remains between 31.3 inches of water at a bladder volume of about 4.5 times the uninflated bladder volume (4.5 V,) at which time the bladder first touched the relatively close container walls (eg l6, l8) and 29 inches of water. The pressure remains at this level throughout the operating range of the wound evacuator and satisfactory results have been obtained at bladder inflations of over 30V,. The total pressure variation over this range was only about 8% of the minimum pressure within the range (29 inches of water). In connection with wound evacuators, the pressure curve of FIG. 5 is considered to have a substantially constant pressure.

The container 12 can be formed of any suitable material such as a moldable plastic, for example, polyvinylchoride. The shape of the container lends itself to being blow molded; however, it could be formed other ways, such as by injection molding. At least a portion 59 of one of the flat side walls l6, 18 preferably is transparent and a calibrated graduated scale 60 is placed along the side thereof in order to enable volumetric measurement of the amount of fluid contained within the evacuator 10. The container 12 also is provided with mounting tabs 61 to which a belt 62 or other support means is attached to facilitate hanging the wound evacuator 10 on a bed or chair or to enable the evacuator to be worn by an ambulatory patient.

Further in accordance with the invention, it is desirable to provide means for preventing accidental sealing of a portion of the container from the outlet port 30, especially during evacuation of fluids within the container 12 which were removed from the patient. One means for avoiding this blockage is to provide a recess 63 in the interior surface of the container walls, particularly in the area leading to and adjacent to the outlet port 30. Such a recess 63 assures the existence of a fluid flow passageway from the interior of the container 12 to the outlet port 30. Also, the interior surface of the container walls can be roughened, such as by injection molding the container, to accomplish the same results (FIG. 6).

Another means for preventing blockage of the outlet port is to provide a surface coating 64 on the interior surface of the container 12, (FIG. 7) or on the exterior surface of the bladder 40, which will lessen adherence of the bladder to the interior of the container. For example, it has been found that chlorinating the surface of a latex bladder or coating the interior surface of a container with a conventional commercially available medical silicon successfully lessens adherence of the bladder to the container walls. Reduction of the adherence of the bladder 40 to the container walls also is of substantial assistance in maintaining the negative pressure substantially constant.

In order to operate the resilient bulb 44 illustrated in FIGS. 2 and 3, it is necessary for the user to place his finger over the air inlet 46 while squeezing the bulb 44 to prevent air from escaping through the air inlet 46 and thereby forcing that air into the inflatable bladder 40. The combined operation of simultaneously closing the air inlet 46 and squeezing the bulb 44 is a safety feature to prevent accidental injection of air or previously removed fluid into the patient since it is unlikely that both steps will accidentally be performed. Furthermore, the relative rigidity of the container 12 also precludes accidental pressurization of the contents of the container 12 by pressing on the sides of the container. Consequently the structure provided by this invention reasonably assures that fluid or air will not be accidentally injected into the patient by accidental pressuring of the container.

With some sacrifice in safety but to simplify the utilization of the wound evacuator 10, another form of resilient bulb such as bulb 66, illustrated in FIG. 8, may be used which eliminates the need for the operator to cover the air inlet in order to effectively inflate the bladder 40. An automatically operating check valve, such as a flapper valve 68, is located on the interior surface of the bulb 66 to normally cover the air inlet and is provided with a small diameter bleed vent 72. In order to inflate the bladder 40 the user squeezes the bulb 66 thereby increasing the pressure within the bulb. This increased pressure forces the flapper valve 68 against the air inlet 70 restricting the amount of air passing through the air inlet to be that small amount which can pass through the bleed vent 72. The pressure differential across the flapper valve 74 between the bulb 66 and the bladder 40 causes the flapper valve 74 to open and permit the air to freely enter the bladder 40. Upon release of the bulb 66, the resiliency of the bulb returns it to its original position increasing the volume within the bulb resulting in a reduced pressure within the bulb. This produces a pressure differential across the flapper valve 68 causing the flapper valve to open and allowing atmospheric air to enter the bulb through the inlet 70 while closing the flapper valve 74 to prevent escape of air from the bladder. After the bladder 40 is inflated sufficiently, and the bulb returns to its normal position, air leaving the bladder 40 flows through the bleed vent 76 in the flapper valve 74, into the bulb 66 and through the bleed vent 72 in the flapper valve 68 and to the atmosphere.

To further protect against accidental ejection of air or liquid through the port 26, a check valve, such as a flapper valve 80, can be mounted adjacent to the port 26 for closing the port 26 upon pressurization of the container, such as if the bulb 44 (or bulb 66) is accidently squeezed. Of course, the check valve 80 does not interfere with the flow of fluid into the container 12 through the wound tubing 28. Furthermore, the port 26 can be formed such that the bladder 40 occludes the port 26 when the bladder is inflated to its intended volume to further ensure against leakage through the port 26 to the patient.

It is also contemplated that a bulb can be used which has the same capacity as a fully inflated bladder. In other words, a single compression of the bulb would be sufficient to complete the inflation of the bladder. With a bulb of this size there is no requirement for an air inlet 46 and a closed system can be formed wherein air from the bulb fills the bladder and, when the bladder deflates, the air returns to the bulb for subsequent use. In such a closed system, a supple bulb, less resilient than the bladder, is used.

SUMMARY It can be seen that the fluid evacuator of this invention is completely self-contained,, portable and totally reliable. It is also easy and inexpensive to manufacture and, therefore, disposable. Of considerable significance are the safety features which prevent the fluid evacuator from being accidentally pressurized in a manner which will inject air or previously removed fluids back to the patient. Furthermore, the negative pressure formed at the inlet port which causes the forced removal of fluid from the patient is substantially constant thereby, (a) avoiding potential injury to the patient which could occur if the negative pressure is too high and (b) ensuring efficient operation of the evacuator throughout the entire operational range of the wound evacuator.

What is claimed is:

l. A self-contained fluid evacuator comprising a substantially rigid, closed container having first and second openings therethrough, said first opening being adapted to receive a conduit, an inflatable member within said container, means for inflating said inflatable member mounted on said container and being in flow communication with the interior of said inflatable member through said second opening, valve means responsive to the difference in pressure between the pressure in the inflation means and in the inflatable member such that said valve means enables fluid to enter the inflatable member from the inflating means at a higher rate than the fluid can leave the inflatable member, said valve means restricting fluid from leaving the inflatable member at a rate greater than a predetermined minimal flow rate.

2. A self-contained fluid evacuator as defined in claim 1 wherein said valve means is a check valve having a bleed passageway therethrough which permits restricted fluid flow through said valve when said valve is closed.

3. A self-contained fluid evacuator as defined in claim 2 wherein the inflating means is a manually operable pump having an outlet, said inflatable member is a resilient bladder attached to the outlet of said pump and said check valve is mounted across the pump outlet.

4. A self-contained fluid evacuator as defined in claim 2 wherein the inflating means is a resilient bulb having an air inlet and an air outlet and wherein said inflatable member is a resilient bladder mounted in flow communication with said air outlet, said check valve being mounted across said air outlet to control the flow of air between said bulb and said bladder.

5. A self-contained fluid evacuator comprising a substantially rigid, closed container having a first port and a second port therethrough, said first port adapted to receive a conduit, a resilient inflatable member within said container, a resilient bulb having an air inlet and an air outlet, said inflatable member being mounted in flow communication with said air outlet, the exterior surface of said bulb adjacent said air inlet being irregular to ensure quick opening of the air inlet, on release of the bulb, valve means responsive to the difference in pressure between the pressure within the bulb and the pressure within the inflatable member, said valve means enabling air to enter the inflatable member from the bulb at a higher rate than air can leave the inflatable member, said valve means restricting air from leaving the inflatable member at a rate greater than a predetermined minimal flow rate.

6. A self-contained fluid evacuator as defined in claim 5 wherein said bulb includes a bead projecting from the exterior surface of said bulb, said air inlet extending through said bead and said bulb.

7. A self-contained fluid evacuator comprising:

a. a substantially rigid, closed container including a bottom wall, first and second spaced apart opposed side walls, third and fourth side walls joined to the opposite ends of said first and said second side walls, said third and fourth side walls being spaced apart a distance greater than the spacing between said first and second walls;

b. a first port communicating with the interior of said container;

c. an inflatable member within said container;

d. means for inflating said inflatable member;

e. means for deflating said inflatable member; and

f. said third and fourth side walls having a configuration which substantially conforms to the shape of the natural unimpeded shape of the adjacent portion of said inflatable member during inflation of said inflatable member to a size substantially equal in volume to the volume of the container effecting substantially constant negative pressure at said first port during deflation of said inflatable member.

8. A self-contained fluid evacuator comprising:

a. a substantially rigid, closed container including a bottom wall, first and second spaced apart opposed side walls, third and fourth side walls joined to the opposite ends of said first and second side walls, said third and fourth side walls being spaced apart further than said first and second side walls and having a transverse outward curvature;

b. a first port communicating with the interior of said container;

c. a resilient inflatable member with said container;

d. means for inflating said inflatable member; and

e. said third and fourth side walls having a radious of transverse curvature which conforms to the shape of the natural unimpeded shape of the adjacent portion of said inflatable member during inflation of said inflatable member to a size substantially equal in volume to the volume of the container effecting substantially constant negative pressure at said first port during deflation of said inflatable member.

9. A self-contained fluid evacuator as defined in claim 8 wherein the radius of transverse curvature of said third and fourth walls is PV /2, where W equals the distance between said first and second side walls.

10. A self-contained fluid evacuator as defined in claim 8 wherein said first and second side walls are substantially flat.

11. A self-contained fluid evacuator as defined in claim 8 wherein said bottom wall has a flat portion to facilitate standing the container on a flat surface.

12. A self-contained fluid evacuator as defined in claim 9 wherein said inflatable member is a substantially cylindrical bladder.

13. A self-contained fluid evacuator as defined in claim 8 including means formed on the interior surface of said container at least a portion of which is adjacent to said first port to provide a fluid-flow passageway thereto.

14. A self-contained fluid evacuator as defined in claim 8 including means on one of the interior surfaces of said container and the exterior surface of said inflatable member for impeding said inflatable member from adhering to the interior surface of said container.

15. A self-contained fluid evacuator as defined in claim 8 wherein said means for inflating said inflatable member is a manually operated pump having an outlet, said inflatable member being attached to the outlet of said pump and including valve means responsive to the pressure differential between the interior of said pump and the interior of said inflatable member, said valve means enabling fluid to enter said inflatable member at a higher rate than said valve enables fluid to leave said inflatable member said valve means restricting fluid from leaving the inflatable member at a rate greater than a predetermined minimal flow rate.

16. A self-contained evacuator as defined in claim wherein said valve means is a check valve having a bleed passageway therethrough which permits restricted fluid-flow through said check valve when said check valve is closed.

17. A self-contained fluid evacuator as defined in claim 16 wherein said pump is a resilient bulb having an air inlet therethrough.

18. A self-contained fluid evacuator comprising:

a. a substantially rigid, closed container including a bottom wall, first and second spaced apart opposed side walls, third and fourth side walls joined to the opposite ends of said first and second side walls,

said third and fourth side walls being spaced apart further than said first and second side walls;

b. a first port communicating with the interior of said container and adapted to receive a conduit;

c. a second port communicating with the interior of said container;

d. a resilient inflatable member within said container;

e. means for inflating said inflatable member mounted on said container and communicating with said inflatable member through said second port;

f. said third and fourth side walls having an effective configuration which conforms to the shape of the natural unimpeded shape of the adjacent portion of said inflatable member during inflation of said inflatable member effecting substantially constant negative pressure of said first port during deflation of said inflatable member.

19. A self-contained fluid evacuator as defined in claim 18 including air expuision control means responsive to the inflation of said inflatable member to terminate the expulsion of air from said container during inflation of said inflatable member when said inflatable member and said third and fourth side walls obtain a predetermined relationship.

20. A self-contained fluid evacuator as defined in claim 19 wherein the said second port is positioned such that said inflatable member occludes said second port when said inflatable member and said third and fourth side walls obtain a predetermined relationship thereby terminating the explusion of air from said container, said predetermined relationship being that further inflation of said inflatable member without occlusion of said first port would produce deformation of said inflatable bladder into a shape which it would not take if said third and fourth walls were nonexistent.

21. A self-contained fluid evacuator for removing fluids from a patient including a substantially rigid container having spaced apart first and second walls, and third and fourth walls spaced apart further than said first and second walls, a first port communicating with the interior of said container, an inflatable member within said container, means for inflating said inflatable member, means for deflating said inflatable member, said container and said inflatable member having a combined configuration so that said third and fourth walls conform in shape to the shape that the natural unimpeded inflatable member obtains during inflation effecting substantially constant negative pressure at said first port during deflation of said inflatable member throughout said predetermined operating range, the container and inflatable member substantially have the following dimension ratios:

D diameter of bladder;

L length of bladder between 3.0 4.0 D,

W width of container between said first and second walls 2.01),; and

R radius of transverse curvature of said third and fourth walls W IZ.

22. A fluid evacuator as defined in claim 21 wherein the largest internal perimeter of said container is not greater than 22 D 

1. A self-contained fluid evacuator comprising a substantially rigid, closed container having first and second openings therethrough, said first opening being adapted to receive a conduit, an inflatable member within said container, means for inflating said inflatable member mounted on said container and being in flow communication with the interior of said inflatable member through said second opening, valve means responsive to the difference in pressure between the pressure in the inflation means and in the inflatable member such that said valve means enables fluid to enter the inflatable member from the inflating means at a higher rate than the fluid can leave the inflatable member, said valve means restricting fluid from leaving the inflatable member at a rate greater than a predetermined minimal flow rate.
 2. A self-contained fluid evacuator as defined in claim 1 wherein said valve means is a check valve having a bleed passageway therethrough which permits restricted fluid flow through said valve when said valve is closed.
 3. A self-contained fluid evacuator as defined in claim 2 wherein the inflating means is a manually operable pump having an outlet, said inflatable member is a resilient bladder attached to the outlet of said pump and said check valve is mounted across the pump outlet.
 4. A self-contained fluid evacuator as defined in claim 2 wherein the inflating means is a resilient bulb having an air inlet and an air outlet and wherein said inflatable member is a resilient bladder mounted in flow communication with said air outlet, said check valve being mounted across said air outlet to control the flow of air between said bulb and said bladder.
 5. A self-contained fluid evacuator comprising a substantially rigid, closed container having a first port and a second port therethrough, said first port adapted to receive a conduit, a resilient inflatable member within said container, a resilient bulb having an air inlet and an air outlet, said inflatable member being mounted in flow communication with said air outlet, the exterior surface of said bulb adjacent said air inlet being irregular to ensure quick opening of the air inlet, on release of the bulb, valve means responsive to the difference in pressure between the prssure within the bulb and the pressure within the inflatable member, said valve means enabling air to enter the inflatable member from the bulb at a higher rate than air can leave the inflatable member, said valve means restricting air from leaving the inflatable member at a rate greater than a predetermined minimal flow rate.
 6. A self-contained fluid evacuator as defined in claim 5 wherein said bulb includes a bead projecting from the exterior surface of said bulb, said air inlet extending through said bead and said bulb.
 7. A self-contained fluid evacuator comprising: a. a substantially rigid, closed container including a bottom wall, first and second spaced apart opposed side walls, third and fourth side walls joined to the opposite ends of said first and said second side walls, said third and fourth side walls being spaced apart a distance greater than the spacing between said first and second walls; b. a first port communicating with the interior of said container; c. an inflatable member within said container; d. means for inflating said inflatable member; e. means for deflating said inflatable member; and f. said third and fourth side walls having a configuration which substantially conforms to the shape of the natural unimpeded shape of the adjacent portion of said inflatable member during inflation of said inflatable member to a size substantially equal in volume to the volume of the container effecting substantially constant negative pressure at said first port during deflation of said inflatable member.
 8. A self-contained fluid evacuator comprising: a. a substantially rigid, closed container including a bottom wall, first and second spaced apart opposed side walls, third and fourth side walls joined to the opposite ends of said first and second side walls, said third and fourth side walls being spaced apart further than said first and second side walls and having a transverse outward curvature; b. a first port communicating with the interior of said container; c. a resilient inflatable member with said container; d. means for inflating said inflatable member; and e. said third and fourth side walls having a radious of transverse curvature which conforms to the shape of the naturaL unimpeded shape of the adjacent portion of said inflatable member during inflation of said inflatable member to a size substantially equal in volume to the volume of the container effecting substantially constant negative pressure at said first port during deflation of said inflatable member.
 9. A self-contained fluid evacuator as defined in claim 8 wherein the radius of transverse curvature of said third and fourth walls is Wc/2, where Wc equals the distance between said first and second side walls.
 10. A self-contained fluid evacuator as defined in claim 8 wherein said first and second side walls are substantially flat.
 11. A self-contained fluid evacuator as defined in claim 8 wherein said bottom wall has a flat portion to facilitate standing the container on a flat surface.
 12. A self-contained fluid evacuator as defined in claim 9 wherein said inflatable member is a substantially cylindrical bladder.
 13. A self-contained fluid evacuator as defined in claim 8 including means formed on the interior surface of said container at least a portion of which is adjacent to said first port to provide a fluid-flow passageway thereto.
 14. A self-contained fluid evacuator as defined in claim 8 including means on one of the interior surfaces of said container and the exterior surface of said inflatable member for impeding said inflatable member from adhering to the interior surface of said container.
 15. A self-contained fluid evacuator as defined in claim 8 wherein said means for inflating said inflatable member is a manually operated pump having an outlet, said inflatable member being attached to the outlet of said pump and including valve means responsive to the pressure differential between the interior of said pump and the interior of said inflatable member, said valve means enabling fluid to enter said inflatable member at a higher rate than said valve enables fluid to leave said inflatable member said valve means restricting fluid from leaving the inflatable member at a rate greater than a predetermined minimal flow rate.
 16. A self-contained evacuator as defined in claim 15 wherein said valve means is a check valve having a bleed passageway therethrough which permits restricted fluid-flow through said check valve when said check valve is closed.
 17. A self-contained fluid evacuator as defined in claim 16 wherein said pump is a resilient bulb having an air inlet therethrough.
 18. A self-contained fluid evacuator comprising: a. a substantially rigid, closed container including a bottom wall, first and second spaced apart opposed side walls, third and fourth side walls joined to the opposite ends of said first and second side walls, said third and fourth side walls being spaced apart further than said first and second side walls; b. a first port communicating with the interior of said container and adapted to receive a conduit; c. a second port communicating with the interior of said container; d. a resilient inflatable member within said container; e. means for inflating said inflatable member mounted on said container and communicating with said inflatable member through said second port; f. said third and fourth side walls having an effective configuration which conforms to the shape of the natural unimpeded shape of the adjacent portion of said inflatable member during inflation of said inflatable member effecting substantially constant negative pressure of said first port during deflation of said inflatable member.
 19. A self-contained fluid evacuator as defined in claim 18 including air expulsion control means responsive to the inflation of said inflatable member to terminate the expulsion of air from said container during inflation of said inflatable member when said inflatable member and said third and fourth side walls obtain a predetermined relationship.
 20. A self-contained fluid evacuator as defined in claim 19 wherein the said second port is positioned such that saiD inflatable member occludes said second port when said inflatable member and said third and fourth side walls obtain a predetermined relationship thereby terminating the explusion of air from said container, said predetermined relationship being that further inflation of said inflatable member without occlusion of said first port would produce deformation of said inflatable bladder into a shape which it would not take if said third and fourth walls were nonexistent.
 21. A self-contained fluid evacuator for removing fluids from a patient including a substantially rigid container having spaced apart first and second walls, and third and fourth walls spaced apart further than said first and second walls, a first port communicating with the interior of said container, an inflatable member within said container, means for inflating said inflatable member, means for deflating said inflatable member, said container and said inflatable member having a combined configuration so that said third and fourth walls conform in shape to the shape that the natural unimpeded inflatable member obtains during inflation effecting substantially constant negative pressure at said first port during deflation of said inflatable member throughout said predetermined operating range, the container and inflatable member substantially have the following dimension ratios: Df diameter of bladder; Lf length of bladder between 3.0 - 4.0 Df Wc width of container between said first and second walls > 2.0Df; and Rc radius of transverse curvature of said third and fourth walls Wc/2.
 22. A fluid evacuator as defined in claim 21 wherein the largest internal perimeter of said container is not greater than 22 Df. 